Journal Article

Parallel sensory compensation following independent subterranean colonization by groundwater salamanders (Eurycea)

Tovar, R.U., Dobbins, B.A., Hartman, N.R., Leelani, S., Devitt, T.J., García, D.M., Gignac, P.M., Cannatella, D.C. and Hillis, D.M.

Record Number:
6944
Year:
2025
Journal:
bioRxiv preprint
Notes:
This version posted March 6, 2025. The copyright holder for this preprint is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license.
PMCID:
https://doi.org/10.1101/2025.03.02.640989
Abstract:
Lineages that have invaded subterranean environments have repeatedly evolved remarkable adaptations to life in darkness. However, observational and experimental studies in additional natural systems are needed to further our understanding of repeated evolution and convergence. In Texas, a radiation of groundwater salamanders (genus Eurycea), with independent invasions of subterranean karstic environments, offers an opportunity to investigate phenotypic convergence, parallel evolution, and the enhancement and regression of sensory systems. Adaptations to a troglobitic life in this clade includes morphological, behavioral, and physiological changes within and among species. Intraspecific and interspecific variation in morphology to the selective pressures of life underground allows for detailed examination of physical, behavioral, and physiological changes associated with subterranean adaptation within a comparative phylogenetic framework. We find a tradeoff between two sensory systems repeated across multiple subterranean Eurycea lineages: the degeneration of the eye and the expansion of the mechanosensory lateral line. The increase in anterior neuromast organs in subterranean lineages was positively correlated with the expression of paired box protein Pax-6, a conserved transcription factor important for vertebrate neurogenesis. Our results show a decreasing trend of PAX-6 labeling in the neuromasts of adult surface salamanders (E. nana) relative to the maintained labeling in subterranean species (E. rathbuni). Our results suggest a tradeoff in resource allocation between the development of optic and anterior lateral line sensory systems in surface and subterranean salamander lineages and provide a starting point for future evolutionary developmental investigations examining the genetic underpinnings of adaptive, repeated evolution in a novel system
Times Cited:
12
Relevent Species:
Eurycea rathbuni (Stejneger 1896)Eurycea robusta (Longley 1978)Eurycea waterlooensis Hillis, Chamberlain, Wilcox and Chippindale 2001Eurycea sp. nov. Hendrickson 1 Eurycea sp. nov. Hendrickson 2 Eurycea braggi (Smith 1968)Eurycea nerea (Bishop 1944)Eurycea spelaea (Stegneger 1892)Eurycea tonkawae Chippindale, Price, Wiens and Hillis 2000Eurycea tridentifera Mitchell and Reddell 1965Eurycea wallacei (Carr 1939)Eurycea sp. New Braunfels [Goricki et al. 2019]